2020-06-07T11:28:22Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1910442019-09-27T10:58:53Zcom_10261_22com_10261_1col_10261_779DIGITAL.CSICadvisorMartínez-Ruiz, AntonioauthorHernansanz-Agustín, Pablo2019-09-19T10:54:38Z2017http://hdl.handle.net/10261/191044[EN] Oxygen is a key molecule for aerobic life. Eukaryotes have evolved towards an aerobic metabolism which has allowed them to adapt to a plethora of environments and to develop into multicellular systems. The proper distribution of oxygen inside the organism is vital for tissue function and its decreased availability, termed hypoxia, can compromise the survival of the organism. Cells, tissues and organs have developed a series of molecular responses in order to adapt to hypoxia. Mitochondria are the main oxygen consumers in most eukaryotic cells and also a major source of production of reactive oxygen species (ROS) that can be used by the cells to trigger redox cell signaling processes. There has been a long debate on whether cells respond to hypoxia by increasing ROS production and their involvement in different responses to hypoxia. Since superoxide anion is the first ROS formed from oxygen reduction by the mitochondrial electron transport chain (ETC), we have focused on its specific detection in acute hypoxia. We have observed that superoxide anion production by the mitochondria is increased in the first minutes of hypoxia and that it decreases thereafter, reaching basal levels before one hour of hypoxia, what we have called a hypoxic superoxide ‘burst’. In order to dissect the mechanism triggering this response, we have studied the role of different mitochondrial ETC complexes and ion transporters in the production of the hypoxic superoxide burst. We observe that complex I, complex III and the mitochondrial sodium/calcium exchanger (NCLX) are necessary for hypoxic ROS production, and that there could be a chain of events among them. Mitochondrial complex I (CI) undergoes ‘deactivation’ in acute hypoxia; this was inversely proportional to the oxygen concentration and could switch its activity to a sodium/proton antiporter. CI deactivation is necessary for the enhancement of mitochondrial sodium/calcium exchange through NCLX, which in turn promoted
depolarization of the mitochondrial inner membrane. Mitochondrial sodium/calcium exchange is
necessary for superoxide production in which complex III would be involved, although the exact source of superoxide has not been determined. We have been able to observe the implication of NCLX in a variety of experimental settings, in which NCLX inhibition alter different responses to hypoxia, such as activation of the HIF pathway and hypoxic pulmonary vasoconstriction. We have assessed that this mechanism operates also in neurons and brain tissue and that treatment with a NCLX inhibitor diminishes cell death in a model of stroke, probably by reducing oxidative damage. These results open a new window in mitochondrial redox biology research due to the involvement of complex I deactivation
and NCLX in superoxide production, which could also have therapeutic implications.engopenAccessDeactive complex I triggers a superoxide signal through NCLX in acute hypoxiatesis 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://digital.csic.es/bitstream/10261/191044/1/hernansanzTD.pdfFileMD5dff749b5a8eb42cce404140783b40f4014393732application/pdfhernansanzTD.pdf